In most cases, “representative studies” represent the first BAC produced for each human herpesvirus. Hahn et al. 2002, Marchini et al. 2001, and Murphy et al. 2002 correspond to creation of BACs for other alternative strains of HCMV. Zhang et al. 2007 and Dulal et al. 2009 refer to the first BACs with a luciferase reporter genes.